1. Field of the Invention
The present invention relates to an image taking apparatus which shoots an image of a subject to obtain a shot image.
2. Description of the Related Art
Conventionally, in a medical field, there is widely used an endoscope apparatus in which a thin and long tube provided at its tip end with a CCD is inserted into a body of a subject being examined and an image in the body of the subject being examined is shot to observe tumor or cerebral thrombosis. According to such an endoscope apparatus, if the inside of the body of the subject being examined is directly shot, it is possible to grasp color or state of nidus that can not easily be observed by a radiation image without externally damaging the subject being examined, allowing easily obtaining of information necessary for determining a course of remedy.
According to such an endoscope apparatus, the inside of the body of the subject being examined is lighted and under this lighted condition, an image in the body is taken. To avoid illumination inconvenience such as halation, generally brightness of a shot image is measured, i.e., photometry, by analyzing the shot image. The illumination for brightening the inside of the body of the subject being examined is adjusted to an appropriate brightness based on the brightness obtained by the photometry.
Here, there are various known analyzing methods in photometry such as an average photometry and a peak photometry. In the average photometry, the average of brightness at locations in a shot image is defined as the brightness of the shot image, while in the peak photometry, brightness of high brightness portion in the shot image is defined as the brightness of the shot image. In many cases, an analyzing method suitable for adjusting the brightness in the picture taking using the endoscope apparatus is varied depending upon a preference of a user who operates the endoscope apparatus and shooting environment. Hence, some endoscope apparatuses have a number of photometric modes having different analyzing methods so that a user can select a desired photometric mode.
When the endoscope apparatus of such a structure is used at a medical site, a user frequently changes a photometric mode to another mode while operating the endoscope apparatus. To enhance the operability, there is proposed an endoscope apparatus which cyclically switches between a plurality of selectable photometric modes by pushing a button upon receiving a pushing operation of a button at a user's hand (see Japanese Patent Application Publication No. 5-228110 for example).
According to the endoscope apparatus described in Japanese Patent Application Publication No. 5-228110, however, since the switching is carried out by pushing the button cyclically, if an unnecessary photometric mode totally unnecessary for a user exists, such unnecessary photometric mode should be pushed to reach a desired photometric mode from the current mode, which is troublesome for a user.
This problem is not limited to the endoscope apparatus, but is common with an image taking apparatus in which a picture is taken while the shooting condition is adjusted by the photometry and the photometric modes are cyclically switched.